Brominated anionic styrenic polymers are excellent flame retardants. Very desirable methods for preparing such polymeric flame retardants are described in U.S. Pat. Nos. 5,677,390; 5,686,538; 5,767,203; 5,852,131; 5,916,978; and 6,207,765.
A characteristic of brominated anionic styrenic polymers such as brominated anionic polystyrene is its propensity to form substantial amounts of small particles and powders when attempts are made to pelletize the product. It appears that upon formation the pellets, unless bound together by an extraneous binding agent or the like, tend to break apart and to revert to small particles and finely-divided powder, typically referred to as “fines”. Because of this characteristic, various conventional pelletizing procedures are unsuitable for producing brominated anionic styrenic polymers essentially free of fines. As can be readily appreciated, the existence of fines in a product of this type this is not only detrimental to the appearance of the pelletized product but in addition is undesired by the consumer.
In order to effectively use brominated anionic styrenic polymers as flame retardants in certain thermoplastic polymers, the use of binding agents or other extraneous materials to maintain the integrity of the flame retardant in pelletized form, is also deemed undesirable by the consumer. Thus, there is a need for a way of producing unadulterated pelletized brominated anionic styrenic polymers that do not form undesirable amounts of fines during their preparation and packaging.